JPS62266885A - Gas laser apparatus - Google Patents

Abstract

PURPOSE:To make it possible to oscillate high power output laser as a whole, by providing a gas cooling radiator between two or more sets of discharge electrode pairs, always cooling laser gas, which is sent to a space between discharge electrodes located on the downstream side, and preventing the decrease in amplification action of light. CONSTITUTION:A laser-gas cooling radiator 11 is provided between two sets of discharge-electrode pairs 3-1 and 3-2 and 3'-1 and 3'-2 so as to cross the flowing direction of gas. Laser gas is made to flow in the direction of an arrow 6 in an airtight container 1. At first, the gas is cooled by a heat exchanger 4. The laser gas, whose temperature is made low, flows into a discharge space 7-1, which is formed by the electrode pair 3-1 and 3-2 on the upstream side of the gas. The gas is excited, and laser light is oscillated and generated. The gas, which has passed the discharge sapce 7-1, and whose temperature becomes high, is sent into a discharge space 7-2, which is formed by the electrode pair 3'-1 and 3'-2 on the downstream side. The laser gas is cooled through the radiator 11, and the temperature is lowered. Therefore, the amplification action of the laser light is not so decreased, and effective oscillation is performed.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is equipped with a high-output and compact gas laser oscillator, and in particular, the two-axis orthogonal formation in which the gas flow direction and the discharge direction are orthogonal is a three-axis orthogonal type. The present invention relates to a gas laser device.

(Prior art) Conventional gas circulation laser devices that use gas as a laser medium can be either an axial flow type in which the three directions coincide, or two depending on the combination of the gas flow direction, discharge direction, and laser beam axis direction. It can be divided into two types: two-axes orthogonal type, in which the directions are the same, and one remaining direction is orthogonal to the previous two directions; (2) three-axis orthogonal type, in which all three directions are orthogonal to each other.

The present invention is applicable to the above-mentioned processing types except for the axial flow type (①), that is, the two-axis orthogonal formation is a three-axis orthogonal type gas circulation type laser device (hereinafter referred to as a gas laser device). It is.

The laser oscillator shown in FIG. 4 is a typical three-axis orthogonal gas laser device.

To outline this, 1 is an airtight container that isolates the gas (laser gas toy) that is the internal laser medium from the outside air, and houses various laser oscillation members inside the container 1. It is being

As this oscillating member, there is a discharge electrode section 3 which is sandwiched between a total reflection mirror and a partial transmission tube (not shown) and is composed of a pair of vertically opposing electrodes. form. Discharge power is injected into the discharge electrode portion 3 from an external power source 2 .

4 is a heat exchanger, 5 is a blower, and the arrow 6 indicates the direction in which the laser gas flows.

In the above configuration, the laser gas sealed in the airtight container 1 is sent into the discharge space 7 by the blower 5, is excited by the discharge in the space 7, performs laser oscillation, and is separated from the laser beam by the partially transmitting mirror. taken out to the outside. The laser gas sent into the discharge space 7 reaches a high temperature within the discharge space 7 and flows out from the discharge space 7. This outflowing laser gas is guided to the heat exchanger 4, cooled, and returned to the blower 5 again.

In this way, the laser gas is forced to circulate within the airtight container 7 in the direction of the arrow 6 shown in the figure.

Now, the above-mentioned laser beam that is oscillated and taken out to the outside has multiple peaks in the cross section perpendicular to the optical axis, which is generally called multimode, when no operation is performed to control the mode F. It has a light intensity distribution. However, it is said that the single mole Y, in which the bead is concentrated at the center of the optical axis, is most suitable for cutting operations.

This single Mor r is obtained by increasing the diffraction loss, and this diffraction loss is expressed by the Fresnel number NF,
Generally, the smaller the Fresnel number NF, the greater the diffraction loss.

It is determined by the Fresnel number Np quadratic formula.

Np=π, where a: laser beam diameter, λ: laser beam wavelength,
d: Optical path between resonators Therefore, in general, Luni trying to obtain a single mode is
All you have to do is make the laser beam diameter smaller and make the optical path between the resonators longer.

For this reason, what has generally been done in the past is to put an aperture in the optical path and to make the optical path wide.

Of these, when the aperture is tightened, the laser output decreases dramatically,
Particularly when trying to obtain a high-output laser, it is not a good idea to rely solely on this aperture, so efforts are being made to lengthen the optical path.

FIG. 8 shows an example of this, in which a laser beam is bent into a U-shape and reciprocates within a discharge space sandwiched between discharge electrodes 3-1 and 3-2.

That is, in the illustrated example, the discharge space formed between the discharge electrodes 3-1 and 3-2, which are arranged vertically opposite to each other, is widened vertically, and the longitudinal sides of both electrodes 3-1 and 3-2 are widened. At one end of the direction, a total reflection mirror 9 and a partial transmission mirror 10 are installed vertically on the same surface 1, and at the other end, two total reflection mirrors are installed vertically and mutually 4.
They are arranged so as to face each other at an angle of 5°, in order to make the optical path of the laser beam twice as long as the discharge area.

Figure 7 shows a cross-sectional view of the discharge section corresponding to the ten examples shown in Figure 8, and generally, as shown in the cross-section in Figure 8, the optical path of the laser beam is connected to a pair of discharge electrodes. 3-1
, 3-2, the inside of the discharge space is folded back parallel to the width direction IC.

This method is a method generally employed in the past.

However, even if the optical path is turned back within one limited discharge space as described above, there is a limit, and it is becoming difficult to increase the optical path length even more than the current situation.

By the way, in such a gas laser device, it is known that the gas temperature has a large effect on the laser output.

The reason for this will be explained using the case of a carbon dioxide laser as an example. Generally, the laser gas components of carbon dioxide laser are C□,
, He e Nt are mixed basic gases, among which CO and N are particularly involved in excitation and oscillation.
, which is a gas of The excitation of the contributing CO2 to the upper level (001>) is dominated by energy transfer due to collision between the base level <000> molecule of CO and the excited nitrogen molecule.

When the CO2 molecules excited in this way transit to the lower 100〉 level, they emit a laser beam with a wavelength of 10.6 μm, and convert the 〈(110〉 level and the 〈020〉 level to the ground level ＜: 0OO).

Then, as the gas temperature rises, ps shifts to the (010) level.
g′J becomes more likely to occur, and the molecules staying at that level increasingly interfere with the relaxation of molecules at (7, (100)) units.

The dependence of the temperature distribution between the levels on the gas is shown in FIG. The figure shows that as the temperature rises, the molecular density at the <1Qo) level increases, and as is clear from the line indicated by (Noot-8100), it increases from the (001) level to <t a O
＞Transition to the level decreases rapidly. 7Here, the stimulated emission ratio, which indicates the rate at which laser light is emitted, is generally given by (NOOI-N100)-, and h
ν Further, the increase in the light intensity △■ when the light travels through the excitation region by 1 is (NOOI-N+0O)fσ△X. However, N0OI and N100 are husband &<00
The number of molecules in the 1> level and the <100> level, σ is the stimulated emission cross section (the range that induces one photon), k is the light intensity, h is the blank constant, and ν is the frequency of the laser beam. It shows U7.

Therefore, the intensity of the laser beam is (NOOI-N100)
However, as mentioned above and as shown in Figure 6, when the temperature rises, the value of (NOOI-N100) decreases rapidly and the I7 output also decreases significantly, so the laser gas is It is desirable to keep it at a low temperature.

Therefore, conventionally, the gas sent into the discharge space is cooled to a low temperature by a heat exchanger beforehand, and by discharging against this low-temperature gas, the value of (N001-N100) is increased. We are trying to increase amplification.

On the other hand, as shown in FIG. 7 and described above, the laser beam is reciprocated within the discharge space 7 to lengthen the optical path, thereby obtaining a single mode suitable for cutting and the like. FIG. 7(a) shows a discharge space 7 sandwiched between a pair of discharge electrodes 3-1 and 3-2.
In this case, the laser beam travels in two rows on the same horizontal plane.
This shows a case in which two laser beams travel in two rows on the same vertical plane within the discharge space 7 between 3 and 2.

In the former case, the spacing between the electrodes can be set to the minimum necessary, and therefore the injection power required for discharge is small, so the power supply does not need to be as large as the left. In the beam 8-2 section located on the upstream side, 2
In this part, the above (
The value of NOOL-N100) is drastically reduced E7, and the light amplification effect is greatly reduced. On the other hand, in the latter case, constantly cooled low-temperature gas is flowing simultaneously through the two beams 8-1 and 8-2, and the low-temperature gas is supplied with a pair of 1. Since the discharge is caused by the discharge, the light amplification effect is also greatly increased. but,
In this case, the distance between the electrodes has to be increased, which means that the discharge starting voltage has to be considerably higher, which results in the problem of having to increase the size of the power supply. The current situation is that it is hardly ever adopted.

(Problems to be Solved by the Invention) As described above, in the conventional gas laser device in which the flow direction of the laser gas and the discharge direction are perpendicular to each other, it is difficult to obtain a single mode that is effective for cutting, etc., and countermeasures have been taken to solve this problem. and 1
2) In order to increase the length of the optical path within the excitation region, the laser beam is configured to be folded back in a U-shape within the excitation region. Although it is effective for increasing laser oscillation, it cannot withstand practical use because it requires a larger power supply, and other methods are generally used. The gap between the electrodes is kept to the minimum necessary, and the laser beam is made to travel in two rows on the same horizontal plane within the discharge space.

However, in this latter method, although it is possible to downsize the power supply, the laser beams are arranged in two rows perpendicular to the gas flow direction, so the optical path on the downstream side of the gas is different from the one on the upstream side. The problem is that the gas that has been heated to a high temperature after being discharged is discharged, and the amplification effect of the laser beam is drastically reduced.

The present invention has been developed with great effort in view of these points, and has the same settings17 as the gap between the electrodes and the power source as before, the optical path that is equal to or longer than the conventional one, and the amplification effect of the laser beam. The object of the present invention is to provide a compact Gannulas laser device that can obtain a high-output single mode without reducing the power.

(Means for Solving the Problems) Therefore, the present invention provides a gas laser device in which the gas flow direction and the discharge direction are perpendicular to each other, in which two or more pairs of discharge electrodes are arranged side by side with their gas flow surfaces aligned. In addition, a gas cooling radiator is interposed between each pair of electrodes, and this is a means for solving the above problems.

(Function) Since a gas cooling radiator is interposed between two or more pairs of discharge electrodes, the laser gas sent between the discharge electrodes located on the downstream side with respect to the gas flow direction is always in a cooled state. Therefore, the decrease in the light amplification effect can be suppressed to a minimum, and a laser with high output can be oscillated as a whole.

In addition, the optical path length in the excitation region of the laser gas can be any length K by setting the number of electrode pairs mentioned above, making it possible to make the optical path length longer than the conventional optical path length, which allows Fresnel The number can be reduced, making it easier to obtain an ideal single mode.

(Embodiment) An embodiment of the gas laser device according to the present invention will be described below with reference to the drawings. 8 The first part is a three-axis orthogonal gas saw 1 which is an embodiment of the present invention.
T! FIG. 2 is a diagram showing an outline of the device, and FIG. 2 shows a cross-section of the same (12), and FIG. 3 shows details of the discharge electrode section.

First, to outline this embodiment with reference to FIGS. 1 and 2, 1 is an airtight container in which a laser gas and various laser oscillation members are housed, and 2 is a discharge power supply to a discharge electrode disposed in the airtight container 1. This is the power source to be injected. In addition to the discharge electrode, the laser member includes a heat exchanger 4 and a blower 5, which are arranged in sequence in the gas flow direction 6.

In this embodiment, a laser gas cooling radiator 11 is installed in the airtight container 1 in addition to the above-mentioned members. The laser gas cooling radiator 11 has two pairs of discharge electrodes 3-1.
．． 3-2, 3'-1, and 3'-2, and is disposed perpendicular to the gas flow direction. In the illustrated example, two sets of the electrode pairs are illustrated, but two or more sets can be arranged side by side if necessary. In that case, it goes without saying that the number of laser gas cooling radiators will also increase.

the two sets of discharge electrode pairs 3-1, 3-2 and 3'-1;
3'-2 are arranged in parallel so that each discharge space is on the same plane and the discharge direction is perpendicular to the gas flow direction.

Part 1. and each electrode pair 3-1, 3-2 and 3'-1, 3'
As shown in FIG. 2, three total reflection mirrors 9 and one partial transmission mirror 10 are disposed on both sides of the laser beam in the longitudinal direction of the laser beam. 2 and 1, 3'
-2 is bent into a U-shape.

Next, the structure of the discharge electrode section will be explained in detail with reference to FIG. Holder 12-1.1
2-2.12-3.12-4 Express the - side 7
The electrode holder supports two pairs of electrodes by, for example, four pillars 14-1.14-2.1. i-3,14
-4, and at the same time, the two sets of four T-body holders are fixedly supported by one insulating board 13, which is the lower two electrode holders. Furthermore, the said; bead] 3
There are two pairs of electrode holders 12-1, 12-2 and 12.
-3. Install the radiator 11 between 12 and 4 via the support 15.
It is permanently installed. FIG. 3 shows an example of the radiator 11.

According to the illustrated example, the radiator 11 is connected to electric j holders 12-1 to 12-1.
12-4 Waveform/corrugation is formed in the longitudinal direction of the
Plate-like bodies whose interiors allow liquid to pass through are stacked in multiple layers with a predetermined gap in the vertical direction, and each plate-like body is connected to a refrigerant injection pipe 11.
' and a discharge pipe (not shown).

As the refrigerant, for example, liquid oxygen, liquid nitrogen, etc. are used.

The constituent materials for the radiator, pillars, etc. are as follows:
For example, it will be understood that an insulating material such as synthetic resin is used as a matter of course. By the way, is the structure of the radiator μl as shown? It is not something that can be achieved by a manufacturer, but can be easily adopted by other manufacturers such as No. 1 Nikam Core.

In this embodiment, with the above-mentioned configuration, the laser gas is circulated in the direction of the arrow 6 in FIG. When discharge power is injected into '-1 and 3'-2 from the power supply 2 to cause discharge, the laser gas is first cooled by the heat exchanger 4 and lowered in temperature, and the laser gas is transferred to the electrode pair 3-1 and 3 on the upstream side of the gas.
-2, and is excited and oscillated there to generate laser light. The gas that passes through this discharge space 7-1 and heats up the cavity passes through the gas cooling fan located between the two electrode pairs, and is then cooled again (17). Downstream side electrode pair 3'-1
, 3'-2 is formed with π and is fed into the discharge space 7-2. The laser gas is lowered and released on the side! Space 7-2
The laser gas is excited and oscillated again in the radiator 11 to generate laser light, but the laser gas sent here is cooled and cooled down through the radiator 11 as mentioned above, so the width of the laser light is reduced. Efficient oscillation is achieved without any extra effort. Since these laser beams travel by bending the electrode pairs into a U-shape, at least the conventional optical path length is ensured.

In other words, according to this embodiment, excitation and oscillation of the laser gas occur sufficiently in the two sets of excitation sections, making it possible to greatly increase the laser output with the same specifications as the conventional similar @placement, and at the same time. This makes it possible to obtain a single mode similar to the conventional one.

Here, in the illustrated example, is the radiation? ! An example in which t' has two pole pairs and I7 is shown below.1. However, if three or more sets of these are used and a radiator is inserted between each set, the output will further increase and the optical path will be lengthened, so a more logical single mode can be obtained. .

(Effects of the Invention) As described above in detail 17, according to the present invention, parallel installation,
By interposing a radiator for gas cooling between two or more pairs of electrodes, the laser gas fed into each discharge space can be maintained at a constant low temperature, and the amplification effect of the laser light is greatly increased. This is expected to increase. Furthermore, the optical path length within the discharge region can be set to any desired length by setting the number of electrode pairs, and at the same time it becomes easier to obtain the large output, making it more ideal than before. A high-power laser beam with a single mode can be obtained.

17. As can be understood from the structure and operation of the low chain, the device of the present invention requires only simple structural changes to the conventional device, and the same power source and other components as the conventional device can be used as is. It does not need to be large-sized, requires less cost, and can utilize electric power to the maximum extent possible.

[Brief explanation of the drawing]

Figure MXx is a sectional view showing an outline of a gas laser device that is an embodiment of the present invention, and Figure 2 is a plan view taken from the A-person arrow in Figure 1.
FIG. 3 is a detailed perspective view of the discharge electrode section according to the device of this embodiment;
Figure 4 is a sectional view showing the outline of a conventional gas laser device, Figure 5 is a diagram explaining the excitation principle of a carbon dioxide laser, and Figure 6 is a CO
□A diagram showing the relative distribution of each rail of molecules as a function of temperature, Figure 7 (al (bl is the conventional 2
A cross-sectional view showing a row of laser beams, FIG. 8 is FIG. 7(b)
FIG. Description of main parts of diagram

Claims (1)

[Claims] In a gas laser device in which the gas flow direction and the discharge direction are perpendicular to each other, two or more pairs of discharge electrodes are arranged in parallel with their gas flow surfaces aligned, and a gas cooling radiator is provided between each pair of electrodes. A gas laser device characterized by intervening.